In a large skillet, heat oil. Cut tortillas into bite-sized pieces, add to skillet and fry until crispy. Add bell pepper, diced onion, tomato and serrano chile to the skillet. Sauté for 2 to 3 minutes or until soft. Beat eggs well add 2 tablespoon of water to eggs. Add eggs to skillet and scramble until done. Top with cheese and heat until melted.